One of the demonstrators, Gleb Latnik, said police insulted them and that one officer even spat in the face of an activist. He said he, and other protesters were released a few hours later.

Moscow police refused to comment.

In St. Petersburg, four activists were detained after unfurling a banner quoting the Olympic Charter's ban on any form of discrimination. The protesters, who gathered on St. Petersburg's Vasilyevsky Island, were quickly rounded up by police, according to Natalia Tsymbalova, a local activist.

Police there also refused any immediate comment.

A Russian law banning gay "propaganda" from reaching minors has drawn strong international criticism and calls for boycott of the Sochi Games from gay activists and others.

Russian law also bans any unsanctioned protests and violators may face fines or prison sentences.

Human Rights First, a rights watchdog based in New York and Washington D.C., quickly condemned the arrests of Russian LGBT activists.

"The most alarming thing is, despite the international attention, the authorities are still bringing more charges under the law and it is being applied on a larger scale," spokesman Shawn Gaylord said in a statement.

All Out, the international group that organized events in 20 cities this week to pressure Olympic sponsors to condemn Russia's "gay propaganda" law, also harshly criticized the detentions of activists.

"This outrageous move directly contradicts the IOC's assurance that Russian laws are in line with the Olympic Charter," said Andre Banks, executive director of All Out.